In the mid 90's we camped at Gettysburg for the weekend with my Boy Scout Troop. McMillan Woods Youth Campground was the exact location.
I was probably 14 or so, maybe 1995/6? The campground bordered a wheat field, and that Friday night me and a few of my friends were walking the old rusty barbwire border of the campground and field. If it wasn't a full moon it was very close to it and very clear. Spots of fog were meandering through the field, very picturesque.
All of a sudden, while we we stared out into the field an object, completely silent flew within several feet of us. It looked like a cartoon swarm of bees, lots of little black dots, and was in the shape of a tear drop. It flew from left to right and dissapared, It was very close and very visible. I don't think it was very big, If I could guess it was no longer than 4 or 5 feet. Everyone of my friends saw it, some even took off running. I wasn't going to be the only one standing there so I ran too. lol.